1. Field of the Invention
The present invention relates to a method and an apparatus or the like for managing documents while giving consideration to security.
2. Description of the Related Art
Recently, image forming apparatuses called, for example, MFPs (Multi Function Peripherals), which have various functions such as a copier function, a scanner function, a fax function and an Ethernet (registered trademark) communications function, have come into widespread use in offices such as companies or government and municipal offices, academic institutions such as schools or research laboratories, stores such as convenience stores, and various other places, and anyone can now easily use the apparatuses. Furthermore, small and inexpensive image forming apparatuses have been marketed lately, and have begun to gain widespread use in households as well.
Due to the widespread use of the image forming apparatuses, users can easily perform operations for, for example, converting a document image made up of text, diagrams, photographs, illustrations or the like depicted on a sheet of paper into electronic data and storing the data on a hard disk in the image forming apparatuses or a server, or copying it on a separate sheet of paper.
As described above, converting documents into electronic data or copying them on a separate sheet of paper can be readily carried out nowadays, so that documents that should be kept classified are more easily leaked to an indefinite number of outsiders. As a result, management of classified information has become important.
Therefore, for example, methods or apparatuses as described in Japanese unexamined patent publication Nos. 2004-320080, 2004-40819, 10-276335 and 2004-228897 have been proposed as methods for protecting document security.
According to the method described in the first publication, a microminiature memory chip is embedded in a sheet of paper. Then, information of an image that is to be recorded on the sheet is stored on the memory chip together with a password. Further, a background pattern for copy prevention is printed on the sheet. In the case of making a legitimate copy from this sheet, an operator is caused to enter a password by a dedicated copier. When the entered password matches the password stored on the memory chip, the image information stored on the memory chip is read for copying.
According to the method described in the second publication, a script to be subjected to encryption processing or a script to be encrypted, recorded and decrypted is read by an image reading portion, and then stored in an image storing portion via an A/D converter. An encryption mode or a decryption mode is selected based on a processing mode and a PIN number that is entered through a PIN number entry portion, and a number analyzing portion analyzes the entered processing mode and PIN number. An address calculation portion calculates a pixel relocation destination address for performing encryption or decryption processing in accordance with the processing mode by such a method in which a solution to a polynomial equation is derived based on the PIN number. Based on this relocation destination address, a pixel rearrangement/reconfiguration portion replaces the image data stored in the image storing portion.
The image forming apparatus described in the third publication includes an image reading portion that converts a script into image data, an image recognition portion that determines whether the script is an encrypted script by analyzing the image data, an encryption portion that encrypts the image data, a decrypting portion that decrypts the image data, an image input/output control portion that control the entire apparatus, an instruction portion that gives various instructions such as a password to the apparatus, and a printer portion that records the image data on recording paper. The image forming apparatus outputs an encrypted script based on a password specified by the original script, and outputs the same image as that of the original script from the encrypted script based on the password.
According to the method described in the fourth publication, data of an electronic text and data of a background pattern image are first loaded into a RAM from an external storage apparatus. Then, entry of permission conditions as digital watermark information is received through a keyboard or a mouse. Next, the entered permission conditions are embedded in the form of digital watermark information in the text data. Then, the text data in which the digital watermark is embedded is combined with the background pattern image loaded into the RAM, thus generating a text image. Then, the generated text image is converted into print data, and the converted print data is output to a printing apparatus.
For example, in the case of circulating a classified document (e.g., a request for managerial decision) among a group of members, each member checks the document passed from the preceding member, and sends it to the next member. When it is necessary to keep the document in his or her possession, each member duplicates the document, and passes the original document or its duplicate (a sheet of paper or electronic data) to the next member. Each member may perform editing such as writing any necessary information in that document or correcting any errors before passing the document to the next member.
When editing of the document is successively performed in this way, it is necessary to correctly keep track of the order of editing, in particular, the sheet or the electronic data in which the latest version of the document is depicted or recorded. That is, it is necessary to carry out document generation management.
Therefore, if a document is duplicated more times than necessary, then some of the duplicates may not be passed in a predetermined order to reach an unexpected member. In such a case, editing of the document may not be carried out successfully. As such, duplicating a document more times than necessary makes document management complicated. Moreover, it poses a security problem, since the document is easily leaked to many and unspecified persons, as described above.
According to the inventions described in the above-mentioned unexamined patent publication documents, it is possible to protect document security to a certain extent. However, it is not possible to carry out document generation management.